Header and tubes of a forced circulation steam generator



Oct. 28, 1952 W. S. PATTERSON ET AL HEADER AND TUBES OF A FORCEDCIRCULATION STEAM GENERATOR Filed July 21, 1948 5 Sheets-Sheet lJNVENTORS Ward S. Patterson BY Erflfld' 1952 w. s. PATTERSON ET AL2,615,434

HEADER AND TUBES OF A FORCED CIRCULATION STEAM GENERATOR 3 Sheets-Sheet2 Filed July 21, 1948 INVENTORS Word S.

Y n we Ern 1952 w. s. PATTERSON ET AL 2,615,434

HEADER AND TUBES OF A FORCED CIRCULATION STEAM GENERATOR Filed July 21,1948' 5 Sheets-Sheet 5 I INVENTOR- Word 3. Patter Patented Oct. 28, 1952HEADER AND TUBES OF AFORCED CTRCU- LATION STEAM GENERATOR Ward S.Patterson, Chappaqua, and Ernest C. Witzke, Baysidc, N. Y., assignors toCombustion Engineering- Superheater, Inc a corporation of DelawareApplication July 21, 1948, Serial No. 39,966

V Claims.

This invention relatesto apparatus for generating steam and particularlyto a steam generator in which there is a controlled forced circulationof the fluid through the steam generating tubes.

In steam generators constructed to operate in this manner, amultiplicity of steam generating tubes are connected to a common headerfrom which they receive their supply of water thereby forming amultiplicity of parallel tube circuits in which steam is generated. Thecommon header may be connected to the discharge of a pump which receivesits water from a steam and water separating drum. The tube circuitsdischarge the steam and water mixture into the steam and waterseparator.

It is essential to distribute the water from the common header into thesteam generating tube circuits in sufficient quantity so that each ofthe tubes will be sufiiciently cooled by the water to protect it againstoverheating and consequent damage under all rates of steaming.

A preferred way of accomplishing such desirable distribution of water toall of the tube circuits which are connected for parallel water flowtherethrough to a manifold or distribution header, has been to provideorifices or resistances at the entrance to each of the tubes. Theseorifices are of smaller diameter than the tube, the diameter beingchosen to present a substantial resistance to the flow of water.Variations in the water resistance through the tube will then have areduced influence upon the total resistance of orifice and tube andconsequently upon the flow of water through the tube as governed by theorifice.

It is essential that the'orificeremain unobstructed by foreign mattersuch as scale particles or sludge during operation because theamount ofwater flow through the tube and the tubes safety depends upon it. Forthis purpose screens or strainers have been provided within thedistribution header at each of the orifices. The screen openings aresmaller than the orifice so as to stop the flow of foreign matter intothe orifice which otherwise might obstruct it. Another means forpreventing obstruction of the orifices has been to provide one or morelarge'strainers between the header containing the orifices and the pumpfor delivering water to the header.

The orifices whether provided with individual strainers or with a commonoutside strainer or strainers must be mounted within the header adjacenteach tube entrancein such a manner that it may readily beremovedfor'cleaningor replacement. Y Y

. ner.

within the furnace comprises a horizontal cylin-' drical steam and waterdrum 5 to which water It is an object of this invention to provideimproved means for mounting orifices Within a header for supplying waterto the tube circuits of a controlled forced circulation steam generator.

How the foregoing, together with other objects and advantages as mayhereinafter appear or are incident to our invention are realized, isillustrated in preferred form in the accompanying drawings, wherein:

Figure 1 is a diagrammatic representation of a forced circulation steamgenerator.

Figure 2 is a cross section through a header taken on line 2-2 of Figure3, showing improved means of mounting and retaining a multiplicity oforifices and their individual strainers opposite a single handholeplate.

Figure 3 is a section taken on line 33 of Figure 2.

Figure 4 is a cross section through a fragment of a header showingimproved means of mounting and retaining a multiplicity of individualorifices within-a header opposite a single handheld plate as shown inFigures 2 and 3.

Figure 5 is an end view of a yoke shown in Figure 4.-

Figure 6 is a cross section through a fragment of a header showinganother form of improved means for mounting and-retaining; amultiplicity of individual orifices within a header opposite av singlehandhole-plate as shown in Figures 2 and 3. Figure '7 is an end viewof ayoke shown in Figure 6.

Figure'8 is a cross section through a header showing another form ofimproved means for mounting and retaining a multiplicity of orificeswithin a header opposite a-single'h'andholef v I Figure 9 is' a crosssection taken-on line 9- 3 of Figure 8 showing a fragment of the headercontaining a group of orifices.

Figure 1 illustrates an embodiment of the invention arranged for steamgeneration. The

steam generator illustrated comprises a furnace chamber l within whichfuel is burned by means such as an oil burner Zarranged to deliver'oilfor combustion in the furnace in a well known man- The boiler 3' havingits heating surface may be supplied through feedpipe 6 and steam may bewithdrawn through pipe l.

The heating surface within the furnace comprises a multiplicity of tubes4 in parallel arrangement connected to a common distribution header 8and passing thenceupwardly along a 3 wall of the furnace l and thence inback-andforth passes upwardly through the upper portion of the furnaceto connect to the steam and water drum 5. A downcomer 9 is connected atits upper end to the bottom portion of drum 5 and at its lower end tothe inlet of a circulation pump H]. The pump is connected at itsdischarge end to distribution header 8 by connections H, 1 la throughstrainer 12. The pump I is driven as by a motor (not shown) andcirculates the water from drum into header 8 through strainer 12, thencethrough all of the tubes 4 and back into drum 5. An offtake l3 removesthe products of combustion from the furnace.

In order to insure a proper distribution of the water among all of thetubes l of the heating surface which are connected in parallel betweenthe header 8 and drum 5, it is essential to provide means such asorifices M, Ma, I42), I40 (as shown in Figs. 2, 5, '7 and 9respectively) for restricting the flow of water at the entrance end ofeach tube. In the absenceof a common strainer I2, individual strainersmay be provided in each orifice mounting l5 as shown in Figure 2.

The present invention is concerned with improved means for mountingorifices within the header and means for retaining groups of saidorifices in place, said groups being accessible through a single handhole in the opposite side of the header.

Figures 2 and 3 show a preferred embodiment of the invention arrangedwithin the distribution header 8. In Figure 2 the distribution header 8is rectangular in cross-section and the steam generating tubes 4 areconnected to the header as by rolling with the inner ends l6 flared outas shown. Fitted into each inner tube end [6 is a cylindrical tubularorifice mounting [5 containing an orifice [4 adjacent the tube end 16and a plug I! at the opposite end. Spaced around the circumference ofsaid tubular structure l5 are slots [8 which serve as a screen forpreventing foreign matter from obstructing the orifice [4.

In this disclosure there are four such members a, b, c and dassociatedwith a group of four adjoining tubes 4. A pair of yokes i9i9' havingarms held against the plugs ll of the four members a, b, c and d asshown serve to maintain those members in position with respect to theassociated tube ends. The two represented yokes 19-49 are held againstthe members a, b, c and d by means of individual stud bolts 20 each ofwhich is fastened at one end to the wall of header 8 between a group oftubes and provided at the other end with a nut 21 which bears againstthe yoke.

Preferably each stud 20 is located at a point corresponding to thecentre of gravity of the area enclosed by the triangle formed by thecentres of members a, b and c or o, b and d of Fig. 3. However inpracticing our invention under certain conditions stud 20 can desirablybe located outside of said centre of gravity but within said respectivetriangle at a point which results in the most economical diagonalligament between said stud hole and a pair of tube holes located at thevertexes of its corresponding triangle; such location also resulting inthe most economical header wall thickness for any given design pressure.

The group of tubes 4 together with the members a, b, c and d and yokesl9-l9 is located opposite a single hand hole 22 which is so constructedand arranged as to permit access to all of the members a, b, c and d andtube ends [6 and the yokes l9-l9', and permits their removal through thehand hole.

Figures 4, 5; 6, '7; 8, 9, show orifice mountings l5a, 15b and I50respectively in which the individual strainer to each orifice (as shownin Figure 2) is omitted and a common strainer l2 (as shown in Figure 1)is provided. The strainer l2 as is well known may deliver. water frompump I0 into the inside of a tubular screen 23 whence the water passesthrough the screen into the housing of strainer 12 surrounding thescreen and thence be delivered via pipe Ila into the header 8. v

In Figures 4, 6 and 8 the wall of each header 8a, 8?) receiving the endsof tubes 4a and 4b respectively is thicker than that shown in Figure 2and the steam generating tubes 4a, 41), project into a shallow bore 24and 2412 respectively and may be welded to the header as shown at 25 and25b. The orifice mounting I5a in Figure 4 is cylindrical in shape and isprovided with a flange 28 and a snap ring groove 21 adjacent its outerend. A shallow bore 28 is provided in the wall of header 8a inconcentric alignment with the bore 24 of the associated tube. Theorifice mounting l5a projects into bore 28. The yoke 19a engages in thisinstance two adjacent orifice mountings [5a and is spaced from the wallof header 8a. The yoke I9a is held against the flanges 26 of the orificemounting 15a. by means of stud bolt 20a and nut 2la. A snap ring 29engages the snap ring groove 21 and bears against the outer end of yokel9a thereby holding the yoke in fixed position with respect to theorifice mounting I511. The orifice plate may be formed integrally withthe orifice mounting or may be a separate member screwed into theorifice mounting so that it may be replaced.

In Figures 6 and '7 orifice mounting l5b adjacent the welded end of eachtube 419 is substantially the same as shown in Figures 4 and 5 exceptthat the bore in the wall of header 8b which receives the orificemember[5b is tapered and the outer wall 30 of orifice mounting I51) issimilarly tapered so as to seat in the tapered bore. The orificemounting 15b is provided with a shoulder 3| which receives yoke [9b. Bytightening nut 2lb of stud bolt 2% the yoke 19b is pressed againstshoulder 3! of orifice member I51) and thereby holds said member firmlyin the tapered bore of header wall 8b.

In Figures 8 and 9 the orifice member [50 is provided with a shoulder260 as shown in Figures 4 and 5 against which a yoke 19c bears. Yoke I90is loosely retained in position by a rod 32 which projects through anopening 33 in the hand hole closure plate 34 and its stem 35. The handhole plate 34 forms a closure for the hand hole opening 220 located inthe wall of header 8c opposite a group of four steam generating tubes 40and their orifices I40. The opening 220 in header wall is of such shapeand size that it provides access to the four associated orificemountings l5c andprovides an opening through which the yoke I and theorifice mountings l5c may be removed from the header.

The hand hole plate 34 is provided with a finished surface 36 whichbears upon a gasket in turn resting against a finished seat 31 in thewall of header 80. To maintain pressure on said gasket a yoke 38 spansthe stem 35 of the hand hole plate and bears against the outside of theheader at 39. A nut 40 engaging the thread on stem 35 is screwed tightlyagainst yoke 38 and thereby compresses the gasket45 between surfaces 36and 31 to form a tight joint. According to the invention we provide anextension of the thread'on stem- 35 and a finished surface ll at the endof said stem. A cap nut 42 engages finished surface 43 which engages agasket 45 I bearing against the stem endsurface ll, 7 (lap nut 42 isprovided with a bore 44 forreceiying the end of rod 32. In ordertoinsure. a tight seal between thesurfaces 4| and 43 rod 32 is made ofsuch length that it will allow a slight clearance at its end projectinginto the bore 4 of 'cap nut 42 .while the ,.other end touches yoke I90.Q o

By the construction shown in Figures 8 and 9 the necessity for tappingholes inside of header 8 for receiving studs as shown in Fig. 2 isavoided as well as the exposure of the threads of studs 29 to corrosion.The finished surface M on the end of stem 35 of closure plate may easilybe applied during the operation of machining the closure.

From the foregoing it will be seen that our '6 generator, aniinletheadenmeans to supply water undenpr'essure tothe header; a=plurality ofsteam generating tubes:.having. their inletiends con-i nected to'the'header; means forming afiow. restricting orifice mounted at theentrance end of-each tube; a first common yoke forretaining inventiveimprovements are extensive in theiradaption and are not to be restrictedto the specific forms here disclosed by way of illustration.

What we claim is: v

1. In a controlled forced circulation steam generator, an inlet header,means to supply water under pressure to the header; a plurality of steamgenerating tubes having their inlet ends connected to the header andincluding groups of three tubes each group of whose entrance locationsare arranged in the pattern of a triangle; means forming aflow-restricting orifice mounted at the entrance end of each tube; acommon yoke for retaining three of said orifices in respectiveengagement with the ends of the aforesaid three tubes which are includedin said triangular grouping; a single member supported from the headerwall at a point within the triangular pattern of said grouping andsubstantially at the center of gravity of its enclosed area, formaintaining said yoke in the orifice retaining position; and meansforming in the header opposite said groups of orifices a handhole whichis adapted to receive a handhole closure, said handhole beingconstructed and arranged to permit access to and removal both of saidyoke and of each of said three grouped orifices out of the header.

2. In a controlled forced circulation steam generator, an inlet header,means to supply water under pressure to the header; a plurality of steamgenerating tubes having their inlet ends connected to the header andincluding groups of three tubes each group of whose entrance locationsare arranged in the pattern of a triangle;

' means forming a flow-restricting orifice and screen therefor mountedat the entrance end of each tube; a common yoke for retaining three ofsaid screens and orifices in respective engagement with the ends of theaforesaid three tubes which are included in said triangular grouping; asingle member supported from the header wall at a point within thetriangular pattern of said grouping and substantially at the center ofgravity of its enclosed area, for maintaining said yoke in the screenand orifice retaining position; and means forming in the header oppositesaid groups of orifices a handhole which is adapted to receive ahandhole closure, said handhole being constructed and arranged to permitaccess to and removal both of said yoke and of each of said threegrouped screens and orifices out of th header. 1

3. In a controlled forced circulation steam a first triangulargroup ofthree of said orifices adjacent their'tube ends, said first groupcomprising orificesa, b and c; a'second' common yoke for retaining asecond triangular group of said orifices adjacent their tubeends,saidsecond group comprising orifices d, b and 0, whereby orificesLbfand' c are retained both by said first yoke and byisaid s'econd yoke;two single retaining members supported from the header, one retainingmember at a point within the triangle ofgsaid first orifice group andsubstantially at the v center of gravity of its enclosed area formaintaining said first yoke in the orifice retaining position, and theother retaining member at a point within the triangle of said secondorifice group and substantially at the center of gravity of its enclosedarea, for maintaining said second yoke in the orifice retainingposition; and means forming in the header opposite said two groups oforifices a handhole which is adapted to receive a handhole closure, saidhandhole being constructed and arranged to permit access to and removalof both said yokes and each of said groups of said orifices out of theheader.

4. In a controlled forced circulation steam generator, an inlet header,means to supply waterunder pressure to the header; a plurality of steamgenerating tubes having their inlet ends connected to the header; meansforming a fiow restricting orifice and screen therefor mounted at theentrance end of each tube; a first common yoke for retaining a firsttriangular group of three of said orifice and screen members adjacenttheir tube ends, said first group comprising orifice and screen membersa, b and c; a second common yoke for retaining a second triangular groupof said orifice and screen members adjacent their tube ends, said secondgroup comprising orifice and screen members (1, b and 0, whereby orificeand screen members I) and c are retained both by said first yoke and bysaid secv ond yoke; two single retaining members supported from theheader, one retaining member at a point within the triangle of saidfirst orifice group and substantially at the center of gravity of itsenclosed area, for maintaining said first for maintaining said secondyoke in the orifice retaining position; and means forming in the headeropposite said two groups of orifices a handhole which is adapted toreceive a handhole closure, said handhole being constructed and arrangedto permit access to and removal of both said yokes and each of saidgroups of said orifice and screen members out of the header.

5. In a controlled forced circulation steam generator, an inlet header,means to supply water under pressure to the header; a plurality of steamgenerating tubes having their inlet ends connected to the header andincluding groups of three tubes each group of whose entrance locationsare arranged in the pattern of a triangle; means forming aflow-restricting orifice mounted at the entrance end of each tube; acommon yoke for retaining three of said orifices in respectiveengagement with the ends of the aforesaid three 7 tubes which areincluded in said triangular grouping; a single member supported from theheader wall at a point within the triangular pattem'of said grouping inthe vicinity of the center of gravity of its enclosed area formaintaining said'yoke in the orifice retaining position; and meansforming in the header opposite said groups of orifices a handhole whichis adapted to receive a handhole closure, said handhole beingconstructed and arranged to permit access to and removal both of saidyoke and of each of said three grouped orifices out of the header.

, WARD S. PATTERSON.

ERNEST C. WITZKE.

REFERENCES CITED The following references are of record in the file ofthis patent:

Number Number 8 UNITED STATES PATENTS Name Date Niclau sse July 14, 1914,Meier Sept. 21, 1915 Miller-et a l. July 3, 1917 Gear -1 Jan. 4, 1921Lamont Jan. 22, 1935 FOREIGN. PATENTS Country Date Great Britain Oct. 6,1927

